Compatibility: Version 6.7.x, 6.8.x and 2003.x

In most cases, it is actually better to run 4D Tools on the data and structure file and compact them before going through an upgrade. However, if you have doubts about unreported or undetected data corruption, DO NOT compact the data file as it may make the corruption worse. Also keep in mind that you always need to keep a copy of the original database (structure and data file) before performing an upgrade.